octeon_ep: fix timeout value for waiting on mbox response

The intention was to wait up to 500 ms for the mbox response.
The third argument to wait_event_interruptible_timeout() is supposed to
be the timeout duration. The driver mistakenly passed absolute time
instead.

Fixes: 577f0d1b

 ("octeon_ep: add separate mailbox command and response queues")
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230810150114.107765-2-mschmidt@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>